Coolant compressor

ABSTRACT

The invention relates to a coolant compressor comprising an electric drive unit, a cylinder housing (1), a crankshaft (3) which can be driven by the electric drive unit, and a piston (2) that can be driven by the crankshaft (3) and is guided in a working volume of the cylinder housing (1) for cyclically compressing a coolant which can be conveyed via a suction valve into the working volume, said suction valve comprising a suction opening (7) and a valve closure element (8), preferably a valve spring, which closes the suction opening (7) in cycles. The aim of the invention is to ensure a continuous opening movement of the suction valve during the suction cycle. According to the invention, this is achieved by providing an actuation device (14; 15, 23) which is designed to open the valve closure element (8) in cycles.

FIELD OF THE INVENTION

The invention relates to a coolant compressor having an electrical driveunit, a cylinder housing, a crankshaft drivable by the electrical driveunit and a piston drivable by the crankshaft, guided in a working volumeof the cylinder housing for cyclical compression of a coolant, which canbe conveyed into the working volume via a suction valve comprising asuction opening and a valve-closing element, preferably a valve springcyclically closing the suction opening.

Generally, a cylinder head arrangement is mounted on the cylinderhousing, the cylinder head arrangement comprising a suction opening anda valve-closing element that cyclically closes the suction opening. As arule, the cylinder head arrangement also comprises a valve plate, whichhas the suction opening and a pressure opening, as well as a cylinderhead cover, which forms a sealed cavity together with the valve plate.The valve-closing element of the suction valve is generally arranged onthe side of the valve plate facing the piston, while a valve-closingelement of the pressure valve that cyclically closes the pressureopening is arranged on the side of the valve plate facing away from thepiston. The suction valve and the pressure valve generally have a valvespring as the valve-closing element. A sealing element, preferably inthe form of a flat gasket, is usually arranged between the valve plateand the cylinder housing or between the valve plate and the cylinderhead cover. The valve plate is generally pressed via the valve headcover onto the cylinder housing.

PRIOR ART

Coolant compressors, especially hermetically encapsulated coolantcompressors having a hermetically sealable compressor housing, have longbeen known and are primarily used in cooling appliances such asrefrigerators or refrigerating shelves. The coolant process as such haslikewise been known for a long time. Coolant is heated in an evaporatorby absorbing energy from a space to be cooled and finally overheated,and is pumped to a higher pressure level by means of the coolantcompressor, by a piston cylinder unit, more specifically by a pistonmoving translationally in a cylinder housing, where the coolant outputsheat via a condenser and is conveyed back into the evaporator via athrottle valve, in which a pressure reduction and a cooling down of thecoolant take place. The movement of the piston is implemented via acrankshaft driven by an electrical drive unit. The electrical drive unitnormally comprises a stator and rotor, wherein the rotor is connectedfor conjoint rotation to the crankshaft in order to drive the pistoncylinder unit.

During a revolution of the crankshaft, the piston is moved linearlyduring the suction cycle from top dead center, in which the distancebetween a piston crown and the valve plate is minimal, to bottom deadcenter, in which the distance between the piston crown and the valveplate is maximal, wherein coolant flows or is drawn in via the suctionopening into a cylinder formed by the cylinder housing. In thesubsequent compression cycle, the valve plate closes the suction openingand the piston moves linearly from bottom dead center to top deadcenter, compressing coolant present in the cylinder. Starting from adefined crank angle, the pressure valve opens and the compressed coolantflows out of the cylinder via the pressure opening.

According to the prior art, the suction valve does not open in thesuction cycle until an opening force that is formed in the cylinder bythe vacuum forming due to the piston movement and acts on the suctionvalve is greater than the closing force of the suction valve. As a rule,the closing force of the suction valve is defined by the spring constantof the valve spring for the suction valve. A disadvantage of the priorart is that an undefined state arises during the opening movement of thesuction valve: as soon as the opening force and the closing force areapproximately equal, the suction valve opens and coolant flows into thecylinder. This reduces the vacuum, however, and correspondingly also theopening force acting on the suction valve, so that the suction valvecarries out a closing movement while it should actually be passingthrough the opening movement. Thus a “fluttering” of the suction valveoccurs in a certain crank angle range, in which the suction valve doesnot carry out a continuous opening movement but instead only opensoffset in the intermediate period, or even passes through a closingmovement or several successive closing movements. This firstly reducesthe quantity of total coolant reaching the cylinder during the suctioncycle, which results in reduced efficiency of the coolant compressor.Secondly, the “fluttering” of the suction valve leads to a pulsation ofthe coolant in the coolant circuit, which results in an undesiredincrease of the noise level from the coolant compressor.

OBJECTIVE OF THE INVENTION

An objective of the invention is therefore that of overcoming thedrawbacks of the prior art and proposing a coolant compressor in which acontinuous opening movement of the suction valve during the suctioncycle is ensured.

PRESENTATION OF THE INVENTION

According to the invention, this problem is solved in a coolantcompressor of the type mentioned above by providing an actuating devicewith which the valve-closing element of the suction valve can becyclically opened. The actuating device is thus designed to open thevalve-closing element cyclically. Cyclically means that the actuatingdevice fundamentally opens the valve-closing element in every suctioncycle of a working cycle, where a working cycle corresponds to onerevolution of the crankshaft. In other words, the valve-closing elementis opened in the suction cycle of each working cycle during theoperation of the coolant compressor, in which a plurality of workingcycles are passed through successively.

The actuating device according to the invention is a device that isprovided in addition to the piston, which, in the case of a valve springaccording to the prior art, opens the valve spring merely by drawing incoolant in the suction cycle. The actuating device according to theinvention can carry out the opening of the suction valve on its own or,as in the case of a valve spring, in support of the piston. For thelatter case, it can thus be provided that the valve-closing element canonly be opened on a supporting basis by the actuating device.

Generally speaking, the objective is thus achieved in that the suctionvalve is not opened passively or not only passively by the increasingvacuum in the cylinder during the suction cycle, but the suction valveis actively opened via the actuating device in order to prevent the“fluttering” of the suction valve.

It can be provided that the actuating device has a contact portion thatis engaged with, or can be brought into engagement with, thevalve-closing element, wherein the valve-closing element can be openedcyclically by moving the contact portion. The actuating device is thusdesigned to open the valve-closing element cyclically by moving thecontact portion. This embodiment variant corresponds to a mechanicalactuation of the valve-closing element. A contact portion is moved andopens the valve-closing element in this case. The contact portion canalso be fixedly connected to the valve-closing element and actuated by adifferent element of the actuating device. For example, thevalve-closing element can have a contact portion that protrudes outwardthrough the suction opening and is actuated outside the suction openingby a different element of the actuating device. Or the contact portionis fixedly connected to the valve-closing element at one end and, at theother, is also mechanically connected to the piston (directly as asingle element of the actuating device or indirectly via additionalelements) and is moved by the piston, which thus (also) opens thevalve-closing element mechanically via a tensile force due to themovement of the piston in the suction cycle. Or the contact portion isfixedly connected to a different element of the actuating device and isbrought into engagement with the valve-closing element at leastcyclically. The contact portion can also contact the valve-closingelement only during a defined part of the suction cycle, but not duringthe compression cycle. Or it contacts the valve closing element evenduring the compression cycle but does not exert any force on thevalve-closing element during the compression cycle.

One embodiment provides that the contact portion is or can be broughtinto contact with the side of the valve-closing element facing away fromthe piston in order to open the element by exerting a pressure force.This embodiment is easy to implement in existing coolant compressors,because no retrofitting of elements in the working volume or on thepiston is necessary. This embodiment makes it possible to control theopening of the suction valve by the actuating device without impairingthe operation of the coolant compressor, and to keep the number ofcomponents in the actuating device as small as possible. The suctionvalve generally opens in the direction of the cylinder and is arrangedon the side of the valve plate facing the piston. By exerting a pressureforce on the side of the suction valve facing away from the piston, inother words, by pressing on the suction valve from the side of thesuction valve facing away from the piston at the beginning of thesuction cycle, the continuous opening movement of the suction valve canbe ensured in a particularly simple manner.

It can be provided that the opening of the valve-closing element can beinitiated with the actuating device at an equilibrium of the coolantpressure on both sides of the valve-closing element. This is the idealtime for the opening of the valve-closing element and would also avoidthe “fluttering.” This point in time occurs in a defined crank anglerange, but is dependent on the counter pressure, the dead space and thepiston velocity. This point in time could be determined by measuring thepressure on both sides of the valve-closing element, for example, andthe actuating device could be actuated accordingly.

Because the “fluttering” effect only occurs cyclically in a defined,delimitable crank angle range, it is sufficient according to oneembodiment of the invention to open the suction valve cyclically via theactuating device as a function of the crank angle of the crankshaft, sothat the contact portion of the actuating element is in contact with thesuction valve at least in the crank angle range in which the“fluttering” occurs in conventional coolant compressors. The actuatingdevice is thus designed to open the valve-closing element cyclically asa function of the crank angle of the crankshaft. In this way, theclosing movements occurring during “fluttering” are blocked by thecontact with the contact portion of the actuating element. It istherefore advantageous if the contact portion contacts the suction valvealready at a 90° to 60° crank angle before top dead center, i.e. alreadybefore the beginning of the suction cycle, preferably continuously. Itis particularly advantageous if the contact portion does not contact thesuction valve during a large part of the compression cycle in order toprevent undesired opening of the suction valve. A contact can beprovided merely shortly before the beginning of the suction cycle. It isalso conceivable that the suction valve detaches from the contactportion already during the suction cycle, but at least after the openingmovement, so that the abrupt closing movement of the suction valve atthe end of the suction cycle or the beginning of the compression cycleis not hampered by the contact portion.

It can be provided, and not only with regard to interference of thecontact portion during closure of the suction valve, that thevalve-closing element is cyclically closable by means of the actuatingdevice. This would be the case for a completely active suction valve, orif the contact portion is mechanically connected to the piston. Or if afixed connection between actuating device, contact portion andvalve-closing element is provided, so that the contact portion not onlypresses the valve-closing element into the open position but also pullsit back into the closed position.

In order to implement the dependency of the opening movement of thesuction valve in a simple and cost-effective manner, one embodimentprovides a mechanical coupling of the actuating device with thecrankshaft, since the crank angle and thus also the suction cycle andthe compression cycle are naturally defined via the crank angle of thecrankshaft. Outside the working volume, the actuator device comprises anactuating element, which has the contact portion that can be broughtinto contact or is in contact with the valve-closing element. Thus noadditional—often expensive—electrical control elements or actuators arenecessary. The mechanical coupling can be achieved via a wide variety ofkinematic relationships. As will be described below in detail, a singleactuating element, designed as a lever, for example, can be provided. Itis equally conceivable, however, that the actuating device may compriseone or more additional operatively connected actuating element(s).

One embodiment variant of the invention provides that the actuatingelement is connected in an articulated manner to the cylinder housing ora cylinder head cover of a cylinder head arrangement. The cylinder headarrangement typically comprises both a valve plate and a cylinder headcover, and the cylinder head arrangement is secured at a front side ofthe cylinder housing. These components are particularly well-suited forconnecting the actuating element so as to enable easy connection of theactuating element to already existing fastening openings on the cylinderhead cover or on the cylinder housing. The articulated connectionenables a pivoting movement of the actuating element that can achievemovement sequences in the actuating device that are particularly easy tomanage kinematically. The spatial proximity to the suction valve isprovided by a mounting on the cylinder head arrangement or the cylinderhousing.

An additional embodiment of the coolant compressor according to theinvention provides that the actuating element is mounted pivotably abouta pivot axis oriented parallel to the longitudinal axis of thecrankshaft. This type of orientation of the pivot axis ensures that thecontact portion moves in a plane aligned parallel to a bore axis of thesuction opening, wherein the direction of the bore axis correspondssubstantially to the opening direction of the suction valve. An openingmovement of the suction valve can therefore be advantageously supported.Similarly, an orientation of the pivot axis of this kind generally leadsto a lateral arrangement of the actuating element relative to thecylinder housing, because there is not sufficient installation spaceavailable either on the upper side, as viewed in the direction of thelongitudinal axis of the crankshaft, or on the underside of the cylinderhead arrangement, because the installation space is occupied, forexample, by a suction and/or pressure sound absorber.

A preferred embodiment variant of the coolant compressor according tothe invention provides that the actuating device has a control elementin operative contact with an actuating portion of the actuating element,which control element is connected for conjoint rotation to thecrankshaft, wherein actuating element and control element are designedsuch that a rotational movement of the crankshaft can be converted intoa pivoting movement or a translational movement of at least the contactportion of the actuating element. Due to the interaction of the controlelement and the other components of the actuating device, especially theactuating element, the mechanical coupling of the crankshaft can beimplemented simply. The operative connection between the actuatingportion and the control element can be established by direct contact,for example, or by the interposition of additional actuating elements.The control element can be designed in the form of a cam for example, sothat the different radial distances of the side face of the controlelement relative to the longitudinal axis of the crankshaft effect aradial deflection, relative to the longitudinal axis of the crankshaft,of an element of the actuating device in direct contact with the controlelement. In another alternative embodiment variant, the control elementcan also have elevations and depressions in the form of peaks andvalleys on the upper side or the underside of the control element, whicheffect an axial deflection, relative to the longitudinal axis of thecrankshaft, of an element of the actuating device in contact with acontrol element.

If the actuating portion of the actuating element directly contacts thecontrol element, then the actuating portion is deflected by the controlelement during a rotation of the crankshaft. Therefore, a conversion ofthe rotation of the crankshaft by the control element into atranslational movement of the contact portion is fundamentally possible.If the actuating element is designed as a lever, then a pivotingmovement of the contact portion about a fulcrum of the lever is enabled.If the kinematic relationships are chosen appropriately, the pivotingmovement of the contact portion corresponds approximately to atranslational movement.

In another preferred embodiment variant, the actuating device consistsof the actuating element and the control element, so that it is notnecessary to provide any further movable components for kinematicconversion of the crankshaft rotation into a translational movement or apivoting movement of the actuating portion of the actuating elementcontacting the control element.

In order to achieve a simple and cost-effectively producible orinstallable structure of the actuating device, an additional embodimentvariant of the invention provides that the control element has a guidesurface contacting the actuating portion of the actuating element, theguide surface being formed eccentrically to the longitudinal axis of thecrankshaft. Due to the contact between the guide surface and theactuating portion, the eccentric shape of the guide surface directlydeflects the actuating portion radially. The guide surface can bedesigned, for example, as the side face of a cam formed with preferablycircular cross section. Then, a spring element can also be provided,which presses the actuating portion against the control element in orderto ensure the contact between the control element and the actuatingportion. It goes without saying that a guide surface formed in thismanner is also conceivable if there is no direct contact with theactuating portion but rather one or more components of the actuatingdevice are interposed.

Another preferred embodiment variant of the invention provides that theguide surface is formed by an annular-running groove arranged on a sideface of the control element facing the crankshaft or facing away fromthe crankshaft. Due to the interaction of the groove and the actuatingportion, wherein the actuating portion can be shaped like a pin or bolt,the actuating portion is arranged at least in part within the groove.Thereby the actuating portion is moved both radially inward and radiallyoutward by the control element during a revolution of the crankshaft,without the necessity for an additional force such as a spring force tobe exerted on the actuating portion in order to effect deflectioninward. The groove is formed as a closed ring, with a circular orelliptical groove track, wherein both side faces of the groove form aguide surface. To reduce the noise level of the coolant compressor andprevent unbalanced running of the crankshaft, it is advantageous if thecontrol element has a rotationally symmetrical shape relative to alongitudinal axis of the crankshaft.

A particularly preferred embodiment variant of the coolant compressoraccording to the invention provides that the actuating element has alever-shaped main body, wherein a first lever arm of the main body hasthe actuating portion and a second lever arm of the main body has thecontact portion. Easily controllable kinematic relationships can beutilized thanks to the lever shape of the main body so that the movementof the contact portion can be precisely defined by means of the designand dimensioning of the lever arms and the positioning of a fulcrum ofthe lever arm, which in general is used for articulated connection ofthe actuating element to the coolant compressor. Both the contactportion and the actuating portion move on pivoting paths about thefulcrum of the lever arm.

In order to connect the actuating element in an articulated manner tothe cylinder head arrangement, an additional embodiment variant providesthat the cylinder head cover of the cylinder head arrangement forms abearing point for the actuating element, or that a bracket, which formsa bearing point for the actuating element, is mounted on the cylinderhead cover of the cylinder head arrangement. On the basis of theinstallation space available, the fact that the cylinder head cover isgenerally connected by means of fastening elements to the cylinderhousing and the spatial proximity to the suction valve, the cylinderhead cover is particularly suitable for forming the bearing point forthe actuating element. Particularly when retrofitting existing cylinderhead covers with actuating devices, it is advantageous if the bearingpoint is formed by a bracket mounted on the cylinder head cover,preferably by means of the fastening elements for fastening the cylinderhead cover itself. It is fundamentally advantageous if the bearing pointis used for supporting the fulcrum of the lever-shaped main body.

For designing the geometrical shape of the lever-like main body of theactuating element, which is necessary for mechanical coupling of themovement of the contact portion to the crankshaft, an additionalembodiment variant of the coolant compressor according to the inventionprovides that the main body of the actuating element has at least onebend, preferably at least one bend per lever arm, and a bend axis ofeach bend is oriented substantially parallel to the longitudinal axis ofthe crankshaft. The orientation of the bend axis/axes ensures that themain body has at least one continuous base plane, the main bodypreferably being planar in shape. The bends have angle ranges between60° and 160°, more particularly between 90° and 160°, preferably between110° and 150°, and especially preferably between 120° and 140°. In oneadvantageous embodiment, the first lever arm has at least one bend,preferably two bends, of between 115° and 145°, while the second leverarm has a bend of approximately 90°±10°. It is also advantageous if thesecond lever arm extends around the cylinder head cover such that thecontact portion is arranged flush with the suction opening.

In order to minimize the suction losses of the coolant flowing throughthe suction valve that are caused by the actuating device, moreparticularly the contact portion, an additional embodiment variant ofthe invention provides that a cross-sectional area of the contactportion of the actuating element is small relative to a cross-sectionalarea of the suction opening. It is advantageous if the cross-sectionalarea of the contact portion is at most 10% of the cross-sectional areaof the suction opening, preferably at most 5%, more particularly at most2.5%, and especially preferably under 2.5%.

A particularly preferred embodiment variant of the coolant compressoraccording to the invention provides that the contact portion is formedby a resilient contact element, more particularly made from spring wireor plastic. Due to the resilient properties, in particular of the springforce or the plastic, one or more of the following advantageous effectscan be achieved: As a result of the yielding of the contact element, thecontact portion can be brought into contact with the suction valvealready at the end of the ejection cycle, without the valve being open,because the contact element yields elastically. The opening point of thesuction valve can be adjusted precisely by adapting the spring constantof the contact element and the spring constant of the suction valve orof the valve spring of the suction valve. If the actuating element has alever-shaped main body and the region of the actuating element at whichthe contact element is fastened undergoes a pivoting movement, thepivoting movement of the contact portion can be compensated by elasticdeformation if the contact portion is guided at least in certainportions in a guide so that the contact portion and thus the suctionvalve contacted by the contact portion are moved only linearly. If thecontact element is formed from plastic rather than spring wire,resilient properties equal to those when spring wire is used can beformed by selecting the plastic and by the thickness and shape (straightor bent).

Another particularly preferred embodiment variant provides that thecontact element is shaped flat and has a bent connecting portion,wherein the connecting portion optionally connects a preferablylever-shaped main body of the actuating element to the contact portion.Owing to the flat design of the contact element, the spring propertiesof the contact element can be influenced in a particularly simple mannerby the geometric shaping. The resilient properties of the contactelement can be adjusted via the bent connecting portion that is bent insuch a way, for example, that a pivoting movement of the actuatingelement is substantially compensated by torsion of the connectingportion and not by a bending of the contact portion.

An additional especially preferred embodiment variant of the inventionprovides that the contact portion is arranged substantially parallel toa bore axis of the suction opening and that the connecting portion hasat least one V-shaped bend, wherein a plane formed by the contactelement is preferably oriented parallel to the longitudinal axis of thecrankshaft. A contact portion of the contact element, at least portionsof which are inside the cylinder head arrangement, for example insidethe cylinder head cover or inside a suction sound absorber, is generallydesigned to run in a straight line in order to avoid flow losses duringthe inflow of the coolant. A bend of the connecting portion as describedabove can be achieved by at least one V-shaped bending of the connectingportion. It goes without saying that the straight design of the contactportion is advantageous independently of the shape of the bend. Theorientation of the contact element plane ensures that the movement ofthe actuating element can be used directly for continuous opening of thesuction valve.

Another especially preferred embodiment variant of the inventionprovides that the contact portion of the actuating element is guided, atleast in certain sections, in a bore of the cylinder head cover for thecylinder head arrangement and/or in a bore of a suction sound absorber,preferably an outlet of the suction sound absorber. Because the greaterpart of the actuating device is arranged outside the cylinder headarrangement in order not to influence the flow of the coolant and tobridge between the crankshaft and suction valve, it is necessary that atleast the contact portion be guided into the interior of the cylinderhead arrangement in order to be able to contact the suction valve. It istherefore necessary to create an access, which can also serve as a guidefor the contact portion into the interior of the cylinder headarrangement. This access is achieved in certain embodiment variants by abore in the cylinder head cover. A suction sound absorber is usuallyprovided, the outlet of which is directly connected to the suctionopening. Therefore, an opening in the suction sound absorber isnecessary in corresponding cylinder head arrangements in order to guidethe contact portion to the suction valve. If the outlet of the suctionsound absorber is pressed by a portion of the cylinder head cover ontothe valve plate, it can be necessary for the bore to pass through boththe cylinder head cover and the outlet of the suction sound absorber.

In addition to the design of the actuating element as substantially apivotable lever, a translationally movable actuating element is alsopossible. In such a case, the actuating element comprises a firstportion, more particularly a straight portion, that is translationallymovable parallel to the piston, and a second, bent portion that reachesbehind the suction opening and supports the contact portion so that itis likewise movable translationally parallel to the piston. The controlelement, which is connected for conjoint rotation to the crankshaft,could have a guide surface, which is in contact with the actuatingelement and is formed eccentrically with respect to the longitudinalaxis of the crankshaft. The guide surface could be the peripheralsurface of the control element. The control element could be in the formof a cam or an eccentric disc and allow a movement of the actuatingelement in the direction toward the crankshaft at the beginning of thesuction cycle, perhaps by a smaller radius. This movement could beproduced by a spring for example. In this case, the contact portion isalso moved in the direction of the crankshaft and presses thevalve-closing element open from the outside. Thereafter, the actuatingelement moves due to the contact with the control element into aposition remote from the crankshaft, where no pressure is exerted on thevalve-closing element by the contact portion. The straight portion ofthe actuating element can be guided in the cylinder housing. Inparticular, the straight portion of the actuating element can be guidedthrough the valve plate so that the bent portion is located completelyin the volume of a cylinder head cover and the contact portion islikewise situated in the volume of a cylinder head cover. Thus, noopenings for passage of the actuating element are necessary in thecylinder head cover.

The present invention also comprises a method for operating a coolantcompressor having an electrical drive unit, a cylinder housing, acrankshaft drivable by the electrical drive unit and a piston that isdrivable by the crankshaft and is guided in a working volume of thecylinder housing for cyclical compression of a coolant, which isconveyed into the working volume via a suction valve comprising asuction opening and a valve-closing element, preferably a valve spring,that cyclically closes the suction opening. An actuating device isprovided, with which the valve-closing element is opened at leastsupportively in a cyclical manner, i.e. once per revolution of thecrankshaft.

In particular, the actuating device has a contact portion that isengaged with, or can be brought into engagement with, the valve-closingelement, wherein the valve-closing element is opened cyclically bymovement of the contact portion.

The further embodiment variants of the method follow from theabove-described operational mode of the coolant compressor according tothe invention.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be explained in detail with reference to anembodiment. The drawings are for the sake of example and are intended topresent the inventive concept, but not to restrict it, much lessreproduce it exhaustively.

Therein:

FIG. 1 shows a plan view of a coolant compressor according to theinvention in a first variant;

FIG. 2 shows a perspective representation of essential components of thecoolant compressor according to FIG. 1;

FIG. 3 shows an additional perspective representation according to FIG.2;

FIG. 4 shows a perspective view of the coolant compressor from FIG. 1;

FIG. 5 shows a section, perpendicular with respect to FIG. 4, throughthe coolant compressor from FIG. 1;

FIG. 6 shows detailed representations of the actuating element fromFIGS. 1-5;

FIG. 7 shows a schematic representation of the crankshaft, the actuatingdevice and a suction valve for selected crank angles;

FIG. 8 shows a plan view of a coolant compressor according to theinvention in a second variant;

FIG. 9 shows a section, perpendicular with respect to FIG. 12, throughthe coolant compressor from FIG. 8;

FIG. 10 shows the plan view from FIG. 1, in a partial section;

FIG. 11 shows a perspective representation of the coolant compressoraccording to FIG. 8, in a sectional view as in FIG. 10;

FIG. 12 shows a perspective view of a coolant compressor according toFIG. 8.

MODES FOR EMBODYING THE INVENTION

FIG. 1 shows a plan view of a coolant compressor according to theinvention, wherein the components of the coolant compressor are enclosedin a hermetically sealable compressor housing, which is not representedhere in order to be able to show the interior of the compressor housing.

The coolant compressor comprises an electrical drive unit comprising astator and a rotor, which is connected for conjoint rotation to acrankshaft 3 (see FIGS. 2 and 3). The crankshaft 3 is drivable by meansof the electrical drive unit, and a piston-cylinder unit operativelyconnected to a crank pin 12 of the crankshaft 3 arranged eccentricallyrelative to the longitudinal axis 4 of the crankshaft 3 cyclically drawsin and compresses coolant. The piston-cylinder unit comprises a cylinderhousing 1 enclosing a cylinder, and a piston 2 translationally guidedtherein (see FIG. 7). The piston 2 is connected via a connecting rod 13to the crank pin 12 of the crankshaft 3 so that the piston 2 passesthrough a suction cycle and a compression and discharge cycle during onerotation of the crankshaft 3 (see FIG. 7).

A cylinder head arrangement 5 sealingly closing off the cylinder isattached to a front side of the cylinder housing 1 and comprises a valveplate 6 having a suction opening 7 and a pressure opening 9. A suctionvalve 8 cyclically closing off the suction opening 7, and a pressurevalve 10 cyclically closing off the pressure opening 9, are arranged onthe valve plate 6, as can be seen in FIGS. 2 and 3. A cylinder head 11(see FIG. 4) that forms a cavity with the valve plate 6 closes off thecylinder head arrangement 5. The cylinder head cover 11 is fastened tothe cylinder housing 1 via multiple fastening elements, in the presentcase four fastening elements, preferably bolts, while the valve plate 6is clamped between cylinder head cover 11 and cylinder housing 1. As arule, sealing elements, preferably flat gaskets, are arranged betweencylinder head 11 and valve plate 6 and between valve plate 6 andcylinder housing 1 in order to guarantee the leak-tightness of thecylinder arrangement 5 relative to the interior of the compressorhousing. The pressure conduit that leads away from the pressure opening9 is formed in this case by the cylinder housing 1, and pressure soundabsorbers 41 are provided for the pressure conduit.

According to the invention, an actuating device 14, coupled mechanicallyto the crankshaft 3, is provided for the suction valve 8 and will bedescribed in detail below. The actuating device 14 comprises anactuating element 15 for actuating the suction valve 8, and a controlelement 23 that is connected for conjoint rotation to the crankshaft 3and is operatively connected to an actuating portion 17 of the actuatingelement 15. The actuating element 15 comprises a lever-shaped main body18 having a first lever arm 19 and a second lever arm 20, the actuatingportion 17 being formed on the first lever arm 19. In the presentembodiment, the actuating portion 17 is arranged in an end portion ofthe first lever arm 19.

The actuating element 15 is articulated to the cylinder head 11 in orderto enable a pivoting movement of the actuating element 15. The pivotaxis 21 of the actuating element 15 is oriented parallel to thelongitudinal axis 4 of the crankshaft 3 in order to achieve an openingmovement of the suction valve 8 by pivoting the actuating element 15about the pivot axis 21. The pivot axis 21 is formed by a bearing point30, which acts as a pivot of the lever-shaped main body 18. The bearingpoint 30 is formed in the present embodiment by a bracket 29 mounted onthe cylinder head cover 11, the bracket 29 being connected to thecylinder head cover 11 by means of fastening elements, in the presentcase two fastening elements; see the two fastening openings in thebracket 29 in FIG. 2. The bracket 29 is arranged to the side of thecylinder housing 1 or the cylinder head cover 11, wherein an upper sideand a lower side are oriented in or opposite to the direction of thelongitudinal axis 4. The bracket 29 is formed as an angle piece; thefirst limb of the bracket 29 bears against the front side of thecylinder head cover 11 and has at least one, preferably two, fasteningopenings, and a second limb of the bracket 29 is aligned parallel to aside face of the cylinder head cover 11 and has the bearing point 30.The bearing point 30 is formed in the present embodiment by a pin thatis guided through a bearing opening of the actuating element 15, or inother words, the lever-shaped main body 18.

In alternative embodiment variants, the bearing point 30 can be formeddirectly on the cylinder housing 1 or on the cylinder head cover 11. Thebearing point 30 can be formed as a pin-shaped protrusion of thecylinder head cover 11, for example.

In prior-art coolant compressors, the suction valve 8 is actuatedpassively by the vacuum forming in the cylinder during the suctioncycle. During the first opening phase of the suction valve 8, when theopening force exerted by the vacuum corresponds substantially to theclosing force of the suction valve 8, coolant flows via the partiallyreleased suction opening 7 into the cylinder, whereby the vacuum isreduced and the opening force again decreases. This results in aso-called “fluttering” of the suction valve 8, which is generally formedby a valve spring. During “fluttering,” the suction valve 8 carries outa closing movement one or more times, until the vacuum has been loweredby the inflowing coolant less strongly than is required for applying theopening force. This effect firstly reduces the efficiency of the coolantcompressor, because in certain phases during the suction cycle, nocoolant or only a small amount of coolant reaches the cylinder. At thesame time, the “fluttering” results in pulsations in the suctionedcoolant flow or in the coolant circuit, which leads to an undesirednoise formation.

FIGS. 2 and 3 show the components of the coolant compressor that areessential to the invention. For the sake of clarity, neither thecylinder head cover 11 nor the cylinder housing 1 of the piston 2 arerepresented, in order not to cover the other components. As mentionedabove, the actuating device 14 is mechanically coupled to the crankshaft3, so that, depending on the crank angle of the crankshaft 3, thecontact portion 16 of the actuating element 15 can be brought intocontact with the suction valve 8 so as to achieve a continuous openingmovement of the suction valve. Due to the fact that the contact portion16 contacts the suction valve 8 at least during the opening movement ofthe suction valve 8 and is moved by means of the mechanical couplingdepending on the crank angle of the crankshaft 3, the suction valve 8 isactively opened by means of the actuating element 15, which, due to thecontact with the contact portion 16, prevents a closing movement of thesuction valve 8 during the opening phase.

In the present embodiment, the second lever arm 20 of the lever-shapedmain body 18 of the actuating element 15 comprises the contact portion16, wherein the contact portion 16 is preferably aligned flush with thesuction opening 7 and is fastened to or formed in an end region of thesecond lever arm 20. The contact portion 16 is positioned in the regionof the cylinder head arrangement 5, i.e. on the side of the valve plate6 opposite from the cylinder housing 1 or the piston 2, so that thecontact portion 16 can be contacted with the side of the suction valve 8opposite from the cylinder housing 1 or the piston 2. In that way, thesuction valve 8 can be pressed open by the contact portion 16 becausethe contact portion 16 exerts a pressure force onto the suction valve 8due to the coupled movement.

Since the contact portion 16 protrudes into the space of the cylinderhead arrangement 5, through which coolant flows during the suctioncycle, the contact portion 16 has a small cross section in relation tothe cross-sectional area of the suction opening 7, wherein thecross-sectional area of the contact portion 16 in the present exampleoccupies only approximately 1% of the cross-sectional area of thesuction opening 7 in order to influence the flow of the coolant aslittle as possible.

The mechanical coupling of the actuating device 14 takes place asdescribed below: The control element 23 is shaped like a disk and has arotationally symmetrical outer shape relative to the longitudinal axis4, wherein the crank pin 12 protrudes through an opening 28 of thecontrol element 23. Thereby the control element 23 is arrangedunderneath the connecting rod 13. A guide surface 24, which is arrangedeccentrically relative to the longitudinal axis 4, is formed on anupper, first end face 25 of the control element 23 and in the presentembodiment is in direct contact with the actuating portion 17 of theactuating element 15. The guide surface face 24 is formed by an annulargroove 27 into which the actuating portion 17, formed as a pin forexample, of the actuating element 15 protrudes. The guide surface 24 isformed at least by the two side walls of the groove 27, whereby theactuating portion 17 can be moved in the groove both radially inward andalso radially outward, relative in each case to the longitudinal axis 4.The precise movement sequence will be explained with reference to FIG.7. It is fundamental that, due to the eccentric arrangement of the guidesurface 24, the control element 23 brings about a pivoting movement ofthe actuating element 15 dependent on the crank angle of the crankshaft3, more precisely a pivoting movement of the contact portion 16 aboutthe bearing point 30 or the pivot of the lever-shaped main body 18.Thus, the contact portion 16 moves, depending on the crank angle of thecrankshaft 3, cyclically in the direction of the suction valve 8, inorder to ensure a continuous opening movement of the suction valve 8, orcyclically removes itself from the suction valve 8 in order not tohinder the closing movement of the suction valve 8.

In the present embodiment, the actuating element 15 comprises a contactelement 31 made from spring wire forming the contact portion 16, i.e.spring steel having a diameter of less than 1 mm in the present case,which is fastened in an end region of the second lever arm 20 on thelever-shaped main body 18, preferably by means of a clamping device. Dueto the construction of the contact element 31 from spring wire, it ispossible to adjust a yielding of the contact element 31, for example, inorder to adjust the opening time of the suction valve 8 precisely. Inthe present embodiment, the contact element 31 has a bent connectingportion 32 that connects the contact portion 16 to the actuating element15. The contact element 31 is formed flat; in other words all thebending axes are aligned parallel to one another. The connecting portion32 in the present embodiment has a V-shaped bend, which extends downwardfrom the actuating element 15 at an angle in the direction of thelongitudinal axis 4 and extends upward at an angle in the direction ofthe longitudinal axis 4 after the point of the V. The contact portion 16adjoining the connecting portion 32 is formed straight and is arrangedsubstantially parallel to a bore axis of the suction opening 7, whereinthe contact portion 16 preferably contacts the suction valve 8 in theupper half of the suction opening 7.

FIG. 4 presents an additional perspective representation of the coolantcompressor, showing the cylinder head cover 11 and a suction soundabsorber 33 arranged at least partially inside the cylinder headarrangement 5. The coolant compressor from FIG. 4 is shown in crosssection in FIG. 5, while piston 2 and connecting rod 13 are not drawnin. The control element 23 and the lever 18 were omitted from theactuating device 14 and only the contact element 31 was drawn in. As arule, the coolant flowing into the coolant compressor via a coolantsupply line flows via the suction sound absorber 33 to the suctionopening 7, an outlet 34 of the suction sound absorber 33 being pressedagainst the valve plate 6, preferably via the cylinder head cover 11 ora spring arrangement, in order to establish a nearly gas-tightconnection between the suction sound absorber 33 and the suction opening7. In other words, the suction valve 8 is completely covered by theoutlet 34 of the suction sound absorber 33. In order to bring thecontact portion 16 into contact with the suction valve 8, a bore 35, inwhich at least portions of the contact portion 16 are guided, is formedin the suction sound absorber 33 or in the outlet 34. Due to the smalldiameter of the spring wire and the small gap width between the borewall and the contact element 31, the losses during inflow of the coolantare negligible. If the suction opening 7 is also covered by a portion ofthe cylinder head cover 11 or by some other element of the cylinder headarrangement 5, it is also necessary to provide a bore 35 in the cylinderhead cover 11 or some other element in order to actuate the suctionvalve 8.

FIG. 6 presents detailed representations of the actuating element 15,consisting substantially of the lever-shaped main body 18 and thecontact element 31. A side view, in which the pivot axis 21 of the mainbody 18 is drawn in, is shown at the very top.

Below that there is a plan view from which individual bends 22 a, 22 b,22 c of the main body 18 can be seen. The main body 18 has bends 22 a,22 b respectively in arms 19, 20 and a bend 22 c between the two leverarms 19, 20 at the pivot axis 21. All three bending axes are orientedparallel to the longitudinal axis 4 of the crankshaft 3 (see FIG. 2).The orientation of the bending axes ensures that the main body 18 has acontinuous base plane in which the main body 18 is formed flat, i.e.lies in the plane of the drawing here. The first lever arm 19 has a bend22 a of approximately 140°. The bend 22 c between the two lever arms 19,20 has an angle of approximately 160°, while the second lever arm 20 hasa bend of approximately 90°. The second lever arm 20 can therefore reacharound the cylinder head cover 11 such that the contact portion 16 isarranged aligned with the suction opening 7.

At the lower left in FIG. 6, a perspective view of the actuating element15 from above is shown, and a perspective view of the actuating element15 from below is shown on the right-hand side.

FIG. 7 shows four schematic representations of the crankshaft, actuatingdevice and suction valve 8 at selected crank angles or positions of thepiston 2. At the upper left, the piston 2 is at the end of thecompression cycle, shortly before top dead center. The contact portion16 is already in contact with the suction valve 8, but the latter isstill closed. The contact portion 16 can already be in contact with thesuction valve 8 at 90° to 60° before top dead center.

Only after top dead center does the contact portion 16 enter through thesuction opening and open the suction valve 8 by pressing it inward awayfrom the valve plate 6. This is shown at the upper right in FIG. 7. Thepoint in time or the crank angle starting from which the contact portion16 opens the suction valve 8 is specified here by the geometry of theactuating device 14. The valve 8 is also opened by the vacuum in thecylinder in addition to the contact portion 16.

At the lower left in FIG. 7, the suction cycle has already reached itsend; the piston has moved to just before lower dead center. The contactportion 16 has opened the suction valve 8 even further.

At the lower right, the beginning of the compression cycle is shown,i.e. a piston position shortly after bottom dead center. The contactportion 16 has again left the suction opening 7 and thus no longercontacts the suction valve 8.

FIG. 8 shows a plan view of a coolant compressor according to theinvention in a second variant. The structure of the coolant compressoris substantially identical to that of the first variant in FIGS. 1-7,apart from the actuating device 14.

Here, the actuating device 14 for the suction valve 8, which actuatingdevice is coupled mechanically to the crank shaft 3, comprises anactuating element 36 for actuating the suction valve 8, and a controlelement 37 connected for conjoint rotation to the crankshaft 3. In orderfor the actuating element 36 to be more visible, the cylinder head cover11 has been removed in this figure so that the valve plate 6 is open tothe outside.

The actuating element 36 has the shape of a bent rod with a round crosssection. The actuating element 36 comprises a first portion 38, straightin this case, which is movable translationally parallel to the piston 2,and a second, bent portion 39, which reaches behind the suction opening7 and supports the contact portion 16 such that the latter is likewisemovable translationally parallel to the piston 2. The bent portion herehas the form of a semicircle. The straight contact portion 16 is shorterthan the straight portion 38. The straight contact portion 16 is alignedparallel to the movement direction of the piston 2. The contact portion16 could also be formed as a separate component and/or have a smallercross section than the rest of actuating element 36. The contact portion16 could be designed as a resilient contact element, for example,similar to the contact element 31 from FIGS. 1-7.

If the straight portion 38 moves away from the crank pin 12, the contactportion 16 moves out of the valve plate 6. The contact portion 16 ismoved away from the suction valve 8 in the process. If the straightportion 38 moves toward the crank pin 12, the contact portion 16 canthen pass through the suction opening 7 and open the suction valve 8.

The actuating element 36 is actuated by the control element 37, a diskwith a variable diameter. The control element 37 could simultaneouslycarry out the function of a flywheel. The end of the straight portion 38protrudes from the cylinder housing 1 in the direction of the crankshaft3 or crank pin 12. The end of the straight portion 38 is preloaded bymeans of a spring 40 in the direction of the crank pin 12, so that itcan slide along the outer periphery of the control element 37. In theangle ranges of the control element 37 with a small diameter, i.e.approximately in the lower 180° of control element 37 in FIG. 8, thestraight portion 38 is thus pulled toward the crank pin 12 and thecontact portion 16 opens the suction valve 8. In the angle ranges of thecontrol element 37 having a larger diameter, i.e. in approximately theupper 180° of the outer periphery of the control element 37 in FIG. 8,the end of the straight portion 38 is pressed away from the crank pin 12and thereby the contact portion 16 is pushed out of the valve plate 6(i.e. downward in FIG. 8) and the suction valve 8 can close.

In the cross section of the coolant compressor from FIG. 8 shown in FIG.9, it can be seen that the piston 2 is shortly before its upper deadcenter and thus the compression and discharge cycle is coming to an end.The pressure valve 10 is still opened. Due to the sectional view, thecontact portion 16 cannot be seen here. Only the end of the straightportion 38 is visible, which forms the actuating portion 17 that is inoperative contact with the control element 37. The contact portion 16can already be in contact with the suction valve 8, however, since thebeginning of the suction cycle is imminent. The straight portion 38 ofthe actuating element 36 is guided through the cylinder housing 1,wherein the cylinder housing 1 serves as a guide for the straightportion 38. The bore of the cylinder housing 1 for the straight portion38 is located here at the side underneath the cylinder bore for thepiston 2. Because the straight portion 38 also exits through the valveplate 6, it is possible to accommodate the bent portion 39 inside acylinder head cover 11. The cylinder head cover 11 is not drawn in here,but could be designed as in FIGS. 4 and 5.

Differently from FIGS. 4 and 5, the cylinder head cover 11 in FIGS. 8-12would not have to have an opening for the passage of the actuatingelement 15 or the contact element 16, because the actuating element 36enters into the cylinder head arrangement inside the cylinder head cover11.

In FIG. 10, somewhat more than the left half of the coolant compressorhas been cut away parallel to the drawing plane. The sectional viewalong line A-A is shown in perspective in FIG. 11. FIG. 12 shows aperspective representation of the coolant compressor that has not beencut. Here, it is again visible that the straight portion 38 in thisembodiment is somewhat lower than the contact portion 16. Here too, theguide surface 24 is recognizable as the circumferential surface of thecontrol element 37.

LIST OF REFERENCE NUMBERS

-   1 Cylinder housing-   2 Piston-   3 Crankshaft-   4 Longitudinal axis of crankshaft 3-   5 Cylinder head arrangement-   6 Valve plate-   7 Suction opening-   8 Suction valve-   9 Pressure opening-   10 Pressure valve-   11 Cylinder head cover-   12 Crank pin-   13 Connecting rod-   14 Actuating device-   15 Actuating element-   16 Contact portion of actuating element 15-   17 Actuating portion of actuating element 15-   18 Lever-shaped main body-   19 First lever arm of main body 18-   20 Second lever arm of main body 18-   21 Pivot axis of actuating element 15-   22 Bend

22 a First bend

22 b Second bend

22 c Third bend

-   23 Control element-   24 Guide surface of control element 23-   25 First end face of control element 23-   26 Second end face of control element 23-   27 Groove-   28 Opening-   29 Bracket-   30 Bearing point-   31 Contact element-   32 Connecting portion of contact element 31-   33 Suction sound absorber-   34 Outlet of suction sound absorber 33-   35 Bore-   36 Actuating element-   37 Control element-   38 Straight portion of actuating element 36-   39 Bent portion of actuating element 36-   40 Spring-   41 Pressure sound absorber

1. A coolant compressor having an electrical drive unit, a cylinderhousing, a crankshaft drivable by the electrical drive unit and a pistondrivable by the crankshaft and guided in a working volume of thecylinder housing for cyclical compression of a coolant, which can beconveyed into the working volume via a suction valve comprising asuction opening and a valve-closing element, cyclically closing thesuction opening, wherein an actuating device is provided, which isdesigned to open the valve-closing element cyclically.
 2. The coolantcompressor according to claim 1, wherein the valve-closing element canonly be opened on a supporting basis by the actuating device.
 3. Thecoolant compressor according to claim 1, wherein the actuating devicehas a contact portion that is engaged with, or can be brought intoengagement with, the valve-closing element, wherein the actuating deviceis designed to open the valve-closing element cyclically by moving thecontact portion.
 4. The coolant compressor according to claim 3, whereinthe contact portion is or can be brought into contact with the side ofthe valve-closing element facing away from the piston in order to openthe element by exerting a pressure force.
 5. The coolant compressoraccording to claim 1, wherein the opening of the valve-closing elementcan be initiated with the actuating device at an equilibrium of thecoolant pressure on both sides of the valve-closing element.
 6. Thecoolant compressor according to claims 1, wherein the valve-closingelement is cyclically closable by means of the actuating device.
 7. Thecoolant compressor according to claim 1, wherein the actuating device isdesigned to open the valve-closing element cyclically as a function ofthe crank angle of the crankshaft.
 8. The coolant compressor accordingto claim 1, wherein the actuating device is mechanically coupled to thecrankshaft and comprises an actuating element, which has a contactportion that can be brought into contact or is in contact with thevalve-closing element.
 9. The coolant compressor according to claim 8,wherein the actuating element is connected in an articulated manner tothe cylinder housing or a cylinder head cover of a cylinder headarrangement.
 10. The coolant compressor according to claim 8, whereinthe actuating element is mounted pivotably about a pivot axis orientedparallel to the longitudinal axis of the crankshaft.
 11. The coolantcompressor according to claim 8, wherein the actuating device has acontrol element in operative contact with an actuating portion of theactuating element, which control element is connected for conjointrotation to the crankshaft, wherein actuating element and controlelement are designed such that a rotational movement of the crankshaftcan be converted into a pivoting movement or a translational movement ofat least the contact portion of the actuating element.
 12. The coolantcompressor according to claim 11, wherein the control element has aguide surface contacting the actuating portion of the actuating element,the guide surface being formed eccentrically to the longitudinal axis ofthe crankshaft.
 13. The coolant compressor according to claim 12,wherein the guide surface is formed by an annular groove arranged on anend face of the control element facing the drive unit or on an end facefacing away from the drive unit.
 14. The coolant compressor according toclaim 12, wherein the actuating element has a lever-shaped main body,wherein a first lever arm of the main body has the actuating portion anda second lever arm of the main body has the contact portion.
 15. Thecoolant compressor according to claim 9, wherein the cylinder head coverof the cylinder head arrangement forms a bearing point for the actuatingelement, or in that a bracket is formed on the cylinder head cover ofthe cylinder head arrangement, which bracket forms a bearing point forthe actuating element.
 16. The coolant compressor according to claim 14,wherein the main body of the actuating element has at least one bend,and a bend axis of each bend is oriented substantially parallel to thelongitudinal axis of the crankshaft.
 17. The coolant compressoraccording to claim 3, wherein a cross-sectional area of the contactportion of the actuating element is small relative to a cross-sectionalarea of the suction opening.
 18. The coolant compressor according toclaim 3, wherein the contact portion is formed by a resilient contactelement.
 19. The coolant compressor according to claim 18, wherein thecontact element is shaped flat and has a bent connecting portion,wherein the connecting portion connects the actuating element to thecontact portion.
 20. The coolant compressor according to claim 19,wherein the contact portion is arranged substantially parallel to a boreaxis of the suction opening and that the connecting portion has at leastone V-shaped bend.
 21. The coolant compressor according to claim 3,wherein the contact portion is guided at least in certain sections in abore of the cylinder head cover for the cylinder head arrangement and/orin a bore of a suction sound absorber.
 22. The coolant compressoraccording to claim 8, wherein the actuating element comprises a firstportion, more particularly a straight portion, that is translationallymovable parallel to the piston, and a second, bent portion that reachesbehind the suction opening and supports the contact portion so that itis likewise movable translationally parallel to the piston.
 23. A methodfor operating a coolant compressor having an electrical drive unit, acylinder housing, a crankshaft drivable by the electrical drive unit anda piston drivable by the crankshaft and guided in a working volume ofthe cylinder housing for cyclical compression of a coolant, which isconveyed into the working volume via a suction valve comprising asuction opening and a valve-closing element, cyclically closing thesuction opening, wherein an actuating device is provided with which thevalve-closing element can be opened cyclically at least in a supportingmanner.
 24. The method according to claim 23, wherein the actuatingdevice has a contact portion that is engaged with, or can he broughtinto engagement with, the valve-closing element, wherein thevalve-closing element is opened cyclically by moving the contactportion.
 25. The coolant compressor according to claim 1 wherein thevalve-closing element comprises a valve spring.
 26. The coolantcompressor according to claim 16, wherein the at least one bendcomprises at least one bend per lever arm.
 27. The coolant compressoraccording to claim 18, wherein the resilient contact element is madefrom spring wire or plastic.
 28. The coolant compressor according toclaim 19, wherein the actuating element has a lever shaped main body,and the connecting portion connects the lever-shaped main body of theactuating element to the contact portion.
 29. The coolant compressoraccording to claim 8, wherein the contact element is shaped flat and hasa bent connecting portion, wherein the connecting portion connects theactuating element to the contact portion.
 30. The coolant compressoraccording to claim 29, wherein the actuating element has a lever shapedmain body, and the connecting portion connects the lever-shaped mainbody of the actuating element to the contact portion.
 31. The coolantcompressor according to claim 20, wherein a plane formed by the contactelement is oriented parallel to the longitudinal axis of the crankshaft.32. The coolant compressor according to claim 21, wherein the bore of anoutlet of the suction sound absorber comprises an outlet of the suctionsound absorber.
 33. The method according to claim 23, wherein thevalve-closing element comprises a valve spring.